1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing an object of a folded sheet material. More particularly, the present invention relates to a continuous method and apparatus for manufacturing an object out of a corrugated fiberboard material. Most particularly, the present invention relates to a method and apparatus for making stringers and cross stringers, to be assembled into pallets, from corrugated fiberboard material.
2. Discussion of the Related Art
Methods and apparatus for making stringers and cross stringers from corrugated fiberboard material are shown in the art. U.S. Pat. No. 4,792,325, issued Dec. 20, 1988, to Schmidtke discloses a method and apparatus for continuously making cardboard runners and stringers and assembling them into a cardboard pallet. Whether a runner or stringer is involved, the method involves essentially supplying a fiberboard blank of appropriate composition in size, running the blank through a perforating and scoring roller to produce fold lines in the blank, and progressively folding the blank from the outside in, by passing it through a plurality of curvilinear rods, and supplying adhesive to portions of the blank during the folding process. The runners and stringers thus produced are assembled together to form a cardboard pallet.
U.S. Pat. No. 5,207,631, issued May 4, 1993, to Schmidtke, et. al., shows a method and apparatus for folding of sheet material into symmetrical and non-symmetrical shapes. The method involves, essentially, supplying a sheet of material such as a fiberboard blank of appropriate composition and size, running the blank through crushing and scoring rollers to produce fold lines in the blank, and asymmetrically (making more folds from one side of the blank than from the other side) or symmetrically folding the blank into a predetermined shape while applying adhesive at predetermined points. The blank is folded by passing it through a multi-function folding means, including a lifting means, which can slightly lift the outside edge of the blank until a belt-like folding and propelling means can then fold one panel of a blank over onto the other panel while adhesive is being applied.
While the machines in the art were certainly capable of manufacturing pallet members from corrugated fiberboard material, they proved unsuitable for continuous production use. Problems were encountered with the inability of the machines to handle paper which was over tolerance in thickness, the inability to propel the paper along a flat, horizontal plane of movement through the crushing and scoring sections, instead imparting a slight "S" shape to the paper, and the inability to control the fast moving corrugated paperboard (loss of paper control) in the folding stations. Thus, those skilled in the art continued to search for a high volume production method and apparatus for folding sheet material.